Chemoprotection against cancer by dietary phytochemicals, including indole-3-carbinol (I3C), green tea polyphenols (GTP) and chlorophyllin (CHL) has been demonstrated in animals, but little is known about modulation by phytochemicals of transplacental carcinogenesis or their efficacy and mechanisms of action in humans. Our hypothesis is that these phytochemicals will provide chemoprotection to fetus from PAH-induced transplacental carcinogenesis through blocking mechanisms involving the Aryl Hydrocarbon Receptor (Ahr) (I3C, GTP) or complex formation (CHL). This hypothesis will be tested by: * Examining the role of the Ahr in modulation of transplacental carcinogenesis utilizing the Ahr knockout mouse. * Determining PAH bioavailability to fetal target tissues by DNA 32p-postlabeling analysis. For chemoprotection to be effective transplacentally, phytochemicals must transverse two barriers, the GI and placenta. The Caco-2 cell monolayer system is an excellent in vitro model for GI absorption, metabolism and transport of drugs. The second hypothesis under test is stated in three parts. The Caco-2 cell monolayer in vitro model will (1) predict bioavailability in humans of proposed cancer chemoprotective agents, (2) test hypotheses related to mechanism including modulation of phase I and phase II enzymes and drug transport systems and (3) predict absorption and bioavailability of phytochemicals transplacentally in mice. These hypotheses will be tested by: * Measuring the Kinflux and Keflux, of individual components in GTP, I3C acid condensation products and CHL, singularly, and as mixtures. * Validating the Caco-2 cell monolayer model by administration of select phytochemicals to human volunteers and determining the extent of absorption and identity of serum metabolites. * Determining the potential for these phytochemieals to induce, inhibit and/or be substrates for human intestinal phase I and phase II enzymes and transporters. * Administering phytochemicals to the maternal mouse iv (by-passing GI and first-pass hepatic metabolism) and assessing bioavailability to the fetus to determine if Caco-2 absorption predicts placental bioavailability. These studies provide inportant new information on the efficacy and mechanism(s) of action of cancer chemoprotective phytochemicals.